Gallium nitride (GaN) based devices such as light-emitting diodes (LEDs) and High Electron Mobility Transistors (HEMTs) are grown on a variety of substrates including sapphire, patterned sapphire (PSS), silicon carbide (SiC), GaN and silicon. A device stack may include one or more quantum wells sandwiched between conductive layers (e.g., GaN layers) doped with impurities. The device stack may be grown on a substrate with a crystal structure similar to the crystal structure of the underlying conductive layers. In some applications, the device stack is separated from the substrate after stack growth is complete. However, known separation techniques, such as laser lift-off (LLO), can cause damage to layers of the device stack, increase current leakage, degrade long-term reliability, and reduce overall chip yield.